Electronic recording film



United States Patent 3,407,093 ELECTRONIC RECORDING FILM Noboru Masuda,Tokyo, Japan,'assignor to Denki Onkyo Co., Ltd., Tokyo, Japan, acorporation of Japan No Drawing. Filed Mar. 24, 1965, Ser. No. 442,530 1Claim. (Cl. 117201) ABSTRACT OF THE DISCLOSURE A recording film forelectrostatic recording comprising a film of polyethylene and a coatingof a surface treat ing agent applied on one surface of said film, saidsurface treating agent consisting of polymethacrylic acid and tin metalin chelate combination.

This invention relates to electronic recording films and moreparticularly to electronic recording films made of a synthetic resin andtreated with a special surface treating agent.

When electrostatically recording signals by accumulating electric chargeon a film of a synthetic resin by a direct corona discharge boundelectric field will be created on the rear surface of the film ofsynthetic resin.- As a result, if the recording film is removed from therecord ing machine without any caution the bound electric field would bedisturbed to result in a great distortion in the recorded image orpicture, thus imparing the quality of the picture. An approach to thisproblem has been proposed wherein the recording film is removed from theelectrode after apparent electric charge has been reduced to zero. Byanother method the residual charge is neutralized when the recordingfilm is removed. By still another method a substance having aresistivity of less than ohms is applied in two layers on the rearsurface of the recording film. It has also been proposed to apply ananti-electrostatic paint as the rear surface treating agent which ismore economical than the method of using duplicate layers. Most ofanti-electrostatic paints or agents to prevent accumulation ofelectrostatic charge comprise surface active agents. However it wasfound that these surface active agents greatly affect the quality ofpictures because of their aging characteristic. The principal factorthat contributes to aging is the penetration of the surface active agentapplied on the rear surface of the recording film. Even in a denserecording film made of polyethylene, for instance, the surface activeagent may reach the front surface, or the recording surface of therecording film thus rendering impossible to record in the extreme case.Further as these surface active agents utilize moisture as the carrierof ions, or they are electrolytes they are not effective at lowhumidities.

The object of this invention is to eliminate various defects mentionedabove.

A further object of this invention is to provide novel "ice recordingfilms for electrostatic recording which are effective even at lowerhumidity conditions.

Still further object of this invention is to provide a recording filmfor electrostatic recording wherein aging of the film caused bypenetration of the rear surface treating agent through the film isprevented.

According to this invention the rear surface of a recording film made of:an artificial resin is coated by a film of rear surface treating agentconsisting of a metal chelate resin.

The following example is given by way of illustration and notlimitation.

The substratum of the recording film was made of polyethylene containingless than 10% of lubricant and having a thickness of 0.5 mm. Thepolyethylene film was molded under as far as low humidity condition toprovide smooth surface. One method of synthesizing a rear surfacetreating agent adapted to be applied on the resin film is as follows:

A small quantity of hydrogen peroxide was added to cc. of methacrylicacid and refluxed at a temperature below 160 C. to synthesizepolymethacrylic acid. Ten grams of this polymethacrylic acid wasdissolved in 20 cc. of water and the solution was added dropwisely to asolution consisting of 10 cc. of water and 20 grams of stannic chloridewhile 0.1 N caustic soda was added drop after drop. The temperature wasmaintained in a range of from 40 C. to C. and the mixture was caused toreact for one hour while stirring was continued to obtain a colorlesstransparent compound in which polymethacrylic acid and tin is in chelatecombination. This resin solution was diluted with water or alcohol ofabout 250 times by volume and the diluted resin solution was applied tosaid polyethylene film to produce a recording film.

The rear surface resistivity of the recording film prepared in this waywas less than 10 ohms and the rear surface treating agent adheres wellto the recording film.

In view of the above, it will be evident that many modifications andvariations are possible in light of the above teachings. It therefore isto be understood that within the scope of the appended claim theinvention may be practical otherwise than as specifically described.

What is claimed is:

1. A recording film for electrostatic recording comprising a film ofpolyethylene and a coating of a surface treating agent applied on onesurface of said film, said surface treating agent consisting ofpolymethacrylic acid and tin metal in chelate combination.

References Cited UNITED STATES PATENTS 3,224,889 12/1965 Schnlde et al.117-201 WILLIAM L. JARVIS, Primary Examiner.

